The disclosure of Japanese Patent Application No. 2001-102333 filed on Mar. 30, 2001 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates generally to fluid-filled vibration-damping devices such as an engine mount for use in an automotive vehicle, and more particularly to such a fluid-filled vibration-damping device which is capable of exhibiting a vibration damping effect on the basis of flows of a non-compressible fluid filled therein.
2. Description of the Related Art
A fluid-filled vibration-damping device is known as one type of vibration-damping devices including a vibration damping mount or bushing, which is interposed between two members of a vibration system so as to flexibly connect these two members or mount one of these members on the other member in a vibration damping manner. Such a fluid-filled vibration-damping device is capable of exhibiting a vibration damping effect with the help of resonance or flows of a non-compressible fluid filled in its interior space. Since the fluid-filled vibration-damping device includes a plurality of liquid chambers and orifice passages for permitting flows of the non-compressible fluid between these chambers upon application of a vibrational load to the vibration-damping device, it is generally required to house these chambers and orifice passages within the device with high space utilization so that the device is made simple in construction and compact in size in its entirety.
The present assignee has been disclosed in JP-A-2001-50333 an example of the fluid-filled vibration-damping device, in which a first mounting member and a second mounting member having a generally cylindrical configuration are disposed such that one of opposite open-ends of the second mounting member is opposed to the first mounting member with an axial spacing therebetween, and a rubber elastic body elastically connects the first and second mounting members while fluid-tightly closing the one of opposite open-ends of the second mounting member. The disclosed fluid-filled vibration-damping device further includes a movable rubber plate bonded at its peripheral portion to an annular first support member made of metal and a flexible rubber layer bonded at its peripheral portion to an annular second support member made of metal. These movable rubber plate and the flexible rubber layer are assembled with each other in their axial directions with a given axial spacing therebetween while the first and second support members are held in abutting contact with each other at their outer peripheral portions. The movable rubber plate and the flexible rubber layer thus assembled are fixed to the other open-end of the second mounting member by caulking or fluid-tightly crimping the other open-end of the second mounting member against the mutually laminated outer peripheral portions of the first and second support members, thereby fluid-tightly closing the other open-end of the second mounting member. The rubber elastic body and the movable rubber plate cooperate to define therebetween a primary fluid chamber to which a vibrational load to be damped is applied, and the movable rubber plate and the flexible rubber layer cooperate to define therebetween an auxiliary fluid chamber. The primary and auxiliary fluid chambers are both filled with the non-compressible fluid, and are held in fluid communication through an orifice passage that is disposed between the first and second support members so as to extend circumferentially. The disclosed fluid-filled vibration-damping device constructed as described above can exhibit an excellent vibration damping effect by utilizing resonance of the fluid flowing through the orifice passage induced by a pressure difference between the primary and auxiliary fluid chambers generated upon application of the vibrational load to the device.
An extensive study of the disclosed fluid-filled vibration-damping device by the inventors of the present invention reveals that it is effective to divide the auxiliary fluid chamber by a partition member into an intermediate chamber partially defined by the movable rubber plate and an equilibrium chamber partially defined by the flexible rubber layer, and to form another fluid passage for fluid communication between the intermediate chamber and the equilibrium chamber, for thereby enabling the fluid-filled vibration-damping device to exhibit an excellent vibration damping effect over a wide frequency range, on the basis of the flows of the fluid through the orifice and the fluid passages. Described in detail, the fluid passage for fluid communication between the intermediate and equilibrium chambers is tuned to a frequency band that is different from the frequency band to which the orifice passage is tuned, so that the thus modified fluid-filled vibration-damping device can exhibit a desired vibration damping effect on the basis of the resonance of the fluid that is forced to flow through the orifice and fluid passages with respect to vibrations in a plurality of frequency ranges to which the orifice and fluid passages are tuned respectively.
However, the modified fluid-filled vibration-damping device requires an additional manufacturing step for assembling the partition member in the auxiliary fluid chamber, making it cumbersome to manufacture the device. Therefore, the fluid-filled vibration-damping device suffers from a high manufacturing cost and a deteriorated production efficiency.
It is therefore one object of this invention to provide a fluid-filled vibration-damping device, which is novel in construction, and which makes it possible to easily assemble a partition member into an auxiliary fluid chamber held in fluid communication with a primary fluid chamber through an orifice passage, with simple structure and with high production efficiency, and to effectively form the orifice passage and a fluid passage, which are tuned to different frequency bands. It is another object of the invention to provide a method of producing such a fluid-filled vibration-damping device.
The above and/or optional objects of this invention may be attained according to at least one of the following modes of the invention. Each of these modes of the invention is numbered like the appended claims and depending from the other mode or modes, where appropriate, to indicate possible combinations of elements or technical features of the invention. It is to be understood that the principle of the invention is not limited to these modes of the invention and combinations of the technical features, but may otherwise be recognized based on the teachings of the present invention disclosed in the entire specification and drawings or that may be recognized by those skilled in the art in the light of the present disclosure in its entirety.
(1) A fluid-filled vibration-damping device comprising: (a) a first mounting member; (b) a second mounting member having a generally cylindrical configuration and being spaced apart from the first mounting member with one of axially opposite open-end portions thereof opposed to the first mounting member; (c) an elastic body elastically connecting the first and second mounting member while fluid-tightly closing the one of opposite open-end portions of the second mounting member; (d) a movable rubber plate bonded at a peripheral portion thereof to an annular first support member; (e) a flexible rubber layer bonded at a peripheral portion thereof to an annular second support member, the movable rubber plate and flexible rubber layer being axially assembled with each other and fixed to an other one of axially opposite open-end portions of the second mounting member by means of caulking of the other one of axially opposite open-end portions of the second mounting member against the first and second support members so as to fluid tightly close the other one of opposite open-end portions of the second mounting member such that the elastic body and the movable rubber plate cooperate to form therebetween a primary fluid chamber to which a vibrational load is applied and the movable rubber plate and the flexible rubber layer cooperate to form therebetween an auxiliary fluid chamber, the primary and auxiliary fluid chamber being filled with non-compressible fluid and held in fluid communication with each other through an orifice passage that is formed between the first and second support members so as to extend circumferentially; (f) a partition member disposed in the auxiliary fluid chamber with an peripheral portion thereof forcedly held by and between the first and second support members, so as to divide the auxiliary fluid chamber into an intermediate chamber partially defined by the movable rubber plate and an equilibrium chamber partially defined by the flexible rubber layer; and (g) a fluid passage for fluid communication between the intermediate chamber and the equilibrium chamber, wherein the partition member includes an engaging piece extending toward and being engaged with one of the first and second support members so as to enable the partition member to be provisionally fixed to the one of the first and second support members for assembly of the partition member.
In the fluid-filled vibration-damping device constructed according to this mode of the invention, the partition member is forcedly held by and between the first and second support members and then firmly fixed to these first and second support members, thus eliminating a need of caulking, bonding or another specific arrangement to firmly fix the partition member to the second mounting member. Therefore, the present invention makes it possible to firmly fix the partition member to the second mounting member with ease and with a simple fixing arrangement or structure. Moreover, the engaging piece of the partition member permits a provisional fixing of the partition member to one of the first and second support members, before assembling the first and second support member to the second mounting member. This arrangement makes it possible to automatically install the partition member in position by only assembling the first and second support members with the second mounting member according to the same manner as in the conventional vibration-damping device having no partition member, without requiring any additional arrangement. Thus, the fluid-filled vibration-damping device of the present invention can exhibit high production efficiency. Moreover, the movable rubber plate is directly exposed to the primary fluid chamber over a substantially entire surface area thereof, so that the movable rubber plate provided in the fluid-filled vibration-damping device of the present invention is capable of receiving a pressure of the fluid in the primary fluid chamber in an effective manner.
(2) A fluid-filled vibration-damping device according to the above mode (1), wherein the first and second support members include respective sealing rubbers formed at respective portions by which the peripheral portion of the partition member is forcedly held so that the peripheral portion of the partition member is fluid-tightly forcedly held by and between the first and second support members via the sealing rubbers. In this mode of the invention, a fluid-tight sealing between the intermediate chamber and the equilibrium chamber is effectively enhanced, thus preventing undesirable leakage of the fluid between the intermediate chamber and the equilibrium chamber, allowing the fluid-filled vibration-damping device to exhibit a desired damping effect with high stability. In addition, the partition member is elastically compressed by and between the first and second supporting members via the sealing rubbers, permitting a relatively large amount of tolerance of dimensional errors of the components, thus making it easy to manufacture the fluid-filled vibration-damping device. Preferably, the sealing rubber of the first support member is integrally formed with the movable rubber plate bonded to the first support member, while the sealing rubber of the second support member is integrally formed with the flexible rubber layer bonded to the second support member.
(3) A fluid-filled vibration-damping device according to the above-indicated mode (1) or (2), wherein the first support member has a generally hook-shape in cross section and includes a cylindrical inner sleeve portion and an outward flange portion extending radially outwardly from one of axially opposite end portions of the inner sleeve portion, while the second support member has a generally hook-shape in cross section and includes a cylindrical outer sleeve portion and an inwardly flange portion extending radially inwardly from one of axially opposite end portions of the outer cylindrical portion, the first and second support members being axially assembled with each other such that the inner and outer sleeve portions are opposed to each other with an radial spacing therebetween while the outward and inward flange portions are opposed to each other with an axial spacing therebetween, to thereby form therebetween the orifice passage. This arrangement makes it possible to obtain a relatively large length and a relatively large cross sectional area of the orifice passage, while ensuring a high space utilization, thus providing a comparatively high degree of freedom in tuning the orifice passage. In this respect, the outer sleeve portion of the second annular support member may have a tapered configuration with a diameter gradually decreasing from one of axially opposite ends thereof toward the other. This arrangement is effective to make the fluid-filled vibration-damping device compact in size while assuring a sufficiently large cross sectional area of the orifice passage, thus effectively preventing undesirable interference between the fluid-filled vibration-damping device with other members or devices installed on the vehicle.
(4) A fluid-filled vibration-damping device according to the above-indicated mode (3), further comprising an elastic support member formed on an outer circumferential surface of the inner sleeve portion of the first support member and having an engaging portion formed on an outer circumferential surface thereof, wherein the engaging portion is engageable with the engaging piece of the partition member. This arrangement makes it easy to provisionally fix the partition member to the first support member by only assembling the partition member and the first support member with each other in the axial direction. For instance, the engaging piece of the partition member may be provided with a raised or recessed portion in its inner circumferential portion, while the elastic support member is provided at its outer circumferential surface with a recessed or raised portion whose profile matches to that of the raised or recessed portion formed in the inner circumferential portion of the engaging piece, so that the engaging piece and the engaging portion are engaged with each other with their recessed and raised portion fixed together. Preferably, the engaging piece is provided with an engaging raised portion formed in and protrude radially inwardly from its inner circumferential surface thereof, and the elastic support member is provided with an engaging recessed portion open in its outer circumferential surface. The engaging raised portion of the engaging piece is fitted into the engaging recessed portion of the elastic support member, to thereby engaging the engaging piece and the elastic support member with each other. Preferably, the engaging piece in contact with the elastic support member of the first support member protrudes with an axial length or height that is insufficient to reach the outward flange portion of the first support member, when assembled, for the sake of easiness of dimension control of the components. Yet preferably, the elastic support member of the first support member is integrally formed with the movable rubber plate. When the present mode (4) of the invention is employed together with the above-indicated mode (2), the elastic support member is also integrally with the sealing rubber of the first support member.
(5) A fluid-filled vibration-damping device according to the above-indicated mode (3), wherein the second support member further includes a cylindrical support portion integrally formed at an inner peripheral portion of the inward flange portion thereof, so as to extend axially outwardly, and an elastic support member formed on an inner circumferential surface of the cylindrical support portion and provided with an engaging portion formed at an inner circumferential surface thereof, wherein the engaging portion is engageable with the engaging piece of the partition member. This arrangement makes it easy to provisionally fix the partition member to the second support member by only assembling the partition member and the second support member with each other in the axial direction. Preferably, the elastic support member of the second support member is integrally formed with the flexible rubber layer. When the present mode (5) of the invention is employed together with the above-indicated mode (2), the elastic support member is also integrally with the sealing rubber of the second support member.
(6) A fluid-filled vibration-damping device according to any one of the above-indicated modes (1)-(5), wherein the engaging piece comprises a plurality of engaging pieces that are formed at respective circumferential portions of a peripheral portion of the partition member. According to this mode of the invention, although it is possible to form a cylindrical engaging piece, the engaging pieces are divided and spaced apart from each other in the circumferential direction of the partition member, allowing the engaging pieces to elastically deform with ease. This arrangement makes it easy to provisionally fix the partition member to the first or the second support member by utilizing the engaging mechanism of the raised and recessed portions or the like formed on the engaging pieces and the first or the second support member.
(7) A fluid-filled vibration-damping device according to any one of the above-indicated modes (1)-(6), wherein the fluid passage comprises a through hole formed through the partition member. This arrangement makes it possible to provide the fluid passage with simple structure.